The invention pertains to a hard composite comprising a metal matrix and one or more discrete hard elements held therein wherein the hard composite can be useful as a cutter or a wear member. More particularly, the invention pertains to a diamond composite comprising a matrix composed of carbide-based particulates bonded together by an infiltrant metal with one or more discrete diamond-based elements held therein. It should be understood that the diamond-based element could comprise a discrete-diamond composite or polycrystalline diamond composite having a substrate with a layer of polycrystalline diamond thereon.
Some types of tungsten carbide available for matrix tools include a macrocrystalline tungsten carbide, a crushed sintered cemented macrcocrystalline tungsten carbide having a binder metal (typically cobalt), and a crushed cast tungsten carbide.
Referring to the macrocrystalline tungsten carbide, this material is essentially stoichiometric WC which is, for the most part, in the form of single crystals. Some large crystals of macrocrystalline tungsten carbide are bicrystals. U.S. Pat. No. 3,379,503 to McKenna for a PROCESS FOR PREPARING TUNGSTEN MONOCARBIDE, assigned to the assignee of the present patent application, discloses a method of making macrocrystalline tungsten carbide. U.S. Pat. No. 4,834,963 to Terry et al. for MACROCRYSTALLINE TUNGSTEN MONOCARBIDE POWDER AND PROCESS FOR PRODUCING, assigned to the assignee of the present patent application, also discloses a method of making macrocrystalline tungsten carbide.
Referring to the crushed sintered cemented macrocrystalline tungsten carbide, this material comprises small particles of tungsten carbide bonded together in a metal matrix. For this material as used in this patent application, the crushed sintered cemented macrocrystalline tungsten carbide with a binder (cobalt) is made by mixing together WC particles, Co powder and a lubricant. This mixture is pelletized, sintered, cooled, and then crushed. The pelletization does not use pressure, but instead, during the mixing of the WC particles and cobalt, the blades of the mixer cause the mixture of WC and cobalt to ball up into pellets.
Referring to crushed cast tungsten carbide, tungsten forms two carbides; namely, WC and W.sub.2 C. There can be a continuous range of compositions therebetween. An eutectic mixture is about 4.5 weight percent carbon. Cast tungsten carbide commercially used as a matrix powder typically has a hypoeutectic carbon content of about 4 weight percent. Cast tungsten carbide is typically frozen from the molten state and comminuted to the desired particle size.
In the past, there have been hard composites comprised of a matrix and discrete hard elements held therein. In the typical case, the matrix comprised carbide-based particulates bonded together by an infiltrant metal and the hard elements comprised diamond-based material.
Referring to the carbide-based particulates, one example of the carbide-based component contains about 67.10 weight percent macrocrystalline tungsten carbide having the following size distribution: between 18.0 and 22.0 weight percent of the macrocrystalline tungsten carbide particles have a size of -80 +120 mesh (the mesh size is made according to ASTM Standard E-11-70), between 25.0 to 30.0 weight percent of the macrocrystalline tungsten carbide particles have a size of -120 +170 mesh, between 29.0 weight percent and 33.0 weight percent of the macrocrystalline tungsten carbide particles have a size of -170 +230 mesh, between 18.0 weight percent and 22.0 weight percent of the macrocrystalline tungsten carbide particles have a size of -230 +325 mesh, and up to 5.0 weight percent of the macrocrystalline tungsten carbide particles have a size of -325 mesh. The matrix further contains about 30.90 weight percent crushed cast tungsten carbide particles having a size of -325 mesh, 1.00 weight percent iron that has an average particle diameter of between 3 micrometers and 5 micrometers, and 1.00 weight percent grade 4600 steel having a particle size of -325 mesh.
The 4600 grade steel has the following nominal composition (weight percent): 1.57 weight percent nickel; 0.38 weight percent manganese; 0.32 weight percent silicon; 0.29 weight percent molybdenum; 0.06 weight percent carbon; and balance iron.
Another example of the carbide-based component comprises about 65 weight percent of macrocrystalline tungsten carbide having a particle size of -80 +325 mesh, 27.6 weight percent tungsten carbide rod milled to an average particle size of 4 to 6 micrometers with superfines removed, 2.8 weight percent tungsten having a particle size of -325 mesh, 2.8 weight percent 4600 grade steel having a particle size of -140 mesh, and 1.8 weight percent of iron having a particle size of -325 mesh.
Another example of a carbide-based particulate component comprises 68 weight percent macrocrystalline tungsten carbide having a size of -80 +325 mesh; 15 weight percent of macrocrystalline tungsten carbide having a size of -325 mesh; 15 weight percent of crushed cast tungsten carbide having a size of -325 mesh; and 2 weight percent nickel having a size of -325 mesh. This nickel is INCO type 123 from International Nickel Company and is a singular spike covered regular shaped powder. The chemical analysis and physical characteristics available from commercial literature reveal the following: The chemical analysis shows a composition of: 0.1 max. carbon, 0.15 max. oxygen, 0.001 max. sulfur, 0.01 max. iron, and balance nickel. The average particle size is 3-7 microns (Fisher Subsieve Size), the apparent density is 1.8-2.7 grams/cc, and the specific surface area is 0.34-0.44 m.sup.2 /g.
Still another example of a particulate component comprises a 67.0 weight percent crushed cast tungsten carbide having a particle size distribution as follows: between 18.0 and 22.0 weight percent of the crushed cast tungsten carbide particles have a size of -80 +120 mesh, between 25.0 to 30.0 weight percent of the crushed cast tungsten carbide particles have a size of -120 +170 mesh, between 29.0 weight percent and 33.0 weight percent of the crushed cast tungsten carbide particles have a size of -170 +230 mesh, between 18.0 weight percent and 22.0 weight percent of the crushed cast tungsten carbide particles have a size of -230 +325 mesh, and up to 5.0 weight percent of the crushed cast tungsten carbide particles have a size of -325 mesh. The component further has 31.0 weight percent crushed cast tungsten carbide having a particle size of -325 mesh, 1.0 weight percent iron having a particle size of -325 mesh, and 1.0 weight percent 4600 steel having a particle size of -325 mesh.
One example of a suitable infiltrant comprises 63-67 weight percent copper, 14-16 weight percent nickel, and 19-21 weight percent zinc. This material has a specific gravity of 8.5 g/cc and has a melting point of 1100.degree. F. This infiltrant is used in 1/32 inch by 5/16 inch granules. This alloy is identified as MACROFIL 65 by applicants' assignee, and this designation will be used in this application.
Another example of a suitable infiltrant has a nominal composition of 52.7 weight percent copper, 24.0 weight percent manganese, 15.0 weight percent nickel, 8.0 weight percent zinc, 0.15 weight percent boron, and 0.15 weight percent silicon with traces of lead, tin and iron. This infiltrant is sold by Belmont Metals Inc., 330 Belmont Avenue, Brooklyn, N.Y. 11207, under the name designation "VIRGIN binder 4537D" in 1 inch by 1/2 inch by 1/2 inch chunks. This alloy is identified as MACROFIL 53 by applicants' assignee, and this designation will be used in this application.
While these earlier matrices for a hard composite have performed in a satisfactory fashion, it would be desirable to provide an improved matrix for a hard composite having improved properties. These properties include impact strength, transverse rupture strength, hardness, abrasion resistance, and erosion resistance. It would also be desirable to provide an improved hard composite that uses the improved matrix material. It would still further be desirable to provide a tool member that includes a tool shank with the improved hard composite affixed thereto wherein the tool member could be used, for example, in conjunction with an oil well drill bit.